CAIRO � A hospital in northern Yemen supported by the medical charity Doctors Without Borders was struck by ordnance early Sunday, killing at least four people and causing the collapse of several buildings, the organization said in a statement.

It was the third time in three months that a Doctors Without Borders hospital in Yemen had been damaged or destroyed. At least 10 people were injured in the latest attack, including three of the group�s staff.

The medical charity said it could not confirm which party in Yemen�s civil war had fired what it called a �projectile,� but said that �planes were seen flying over the facility at the time.�

A military coalition led by Saudi Arabia controls the skies over Yemen, and has carried out thousands of bombing runs in the country since entering the war last March. At least one other projectile fell near the hospital, Doctors Without Borders said.

The hospital, called Shiara, is in the northern Saada Province, in the Razeh district near the border with Saudi Arabia. Fierce fighting along the frontier between Saudi troops and Yemen�s Houthi rebels has devastated many border towns and displaced thousands of people, according to aid workers. Attacks on clinics and hospitals have left the province with only one major medical facility, forcing people to travel hours to receive even basic treatment.

In October, coalition warplanes destroyed a Doctors Without Borders clinic in Haydan district, near Razeh. Then, in early December, the coalition bombed one of the group�s mobile clinics in the southern Taiz Province. The Shiara hospital was bombed previously, in September, before Doctors Without Borders became involved with it, the group said.

�All warring parties, including the Saudi-led coalition, are regularly informed of the GPS coordinates of the medical facilities where M.S.F. works,� Raquel Ayora, the director of operations for Doctors Without Borders, said in the statement referring to the group by its French abbreviation.

�We are in constant dialogue with them to ensure that they understand the severity of the humanitarian consequences of the conflict and the need to respect the provision of medical services,� she said. �There is no way that anyone with the capacity to carry out an airstrike or launch a rocket would not have known that the Shiara Hospital was a functioning health facility providing critical services and supported by M.S.F.�

The Saudi-led coalition is fighting to restore the Yemeni President Abdu Rabbu Mansour Hadi, who was driven from power last year by the Houthi rebels, a northern group. More than 2,800 civilians have been killed in the fighting so far, with the majority of people killed by coalition bombing, according to the United Nations.

The Saudi-led coalition, which is backed by the United States and Britain, came under renewed criticism last week for dropping cluster munitions on Sana, the Yemeni capital, killing at least one person.

Human Rights Watch said on Sunday that the Houthis had detained dozens of political opponents and journalists in Sana, which the rebels control. Some of the opponents had vanished with their whereabouts a mystery to their families, the group said. Many of the detainees belonged to Islah, an Islamist political party that opposes the Houthis, Human Rights Watch said.

By The New York Times